From 349407faef7586e6a73a9b69ad73af4c4dbd3029 Mon Sep 17 00:00:00 2001
From: ValarDragon <dojha12@gmail.com>
Date: Mon, 8 Jun 2020 17:18:38 -0500
Subject: [PATCH] Speed up exp_by_const

---
 r1cs-std/src/fields/mod.rs | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/r1cs-std/src/fields/mod.rs b/r1cs-std/src/fields/mod.rs
index 60e22de..51e254f 100644
--- a/r1cs-std/src/fields/mod.rs
+++ b/r1cs-std/src/fields/mod.rs
@@ -242,17 +242,19 @@ pub trait FieldGadget<F: Field, ConstraintF: Field>:
         mut cs: CS,
         exp: S,
     ) -> Result<Self, SynthesisError> {
-        let mut res = Self::one(cs.ns(|| "Alloc result"))?;
+        let mut res = self.clone();
         let mut found_one = false;
 
         for (i, bit) in BitIterator::new(exp).enumerate() {
             if found_one {
-                res.square_in_place(cs.ns(|| format!("square for bit {:?}", i)))?;
+                res = res.square(cs.ns(|| format!("square for bit {:?}", i)))?;
             }
 
             if bit {
+                if found_one {
+                    res = res.mul(cs.ns(|| format!("mul for bit {:?}", i)), self)?;
+                }
                 found_one = true;
-                res.mul_in_place(cs.ns(|| format!("mul for bit {:?}", i)), self)?;
             }
         }